Nano filming plugging agent for drilling fluid and preparation method and application of nano filming plugging agent

Abstract

The invention provides a nano filming plugging agent for a drilling fluid. The nano filming plugging agent comprises the following components: silicon oxide, polyurethane granules, a dispersant and analcohol. By controlling proportions and preparation processes of raw materials, the prepared nano filming plugging agent for the drilling fluid is an odorless white liquid, the density is 1.05g / cm<3>, the granularity of solid particles is 50-400nm, the nano filming plugging agent for the drilling fluid is compressed in the surface of a wall well or microcracks of mud shale to form a semi-permeable isolation film, that is, a complete protection layer is formed on the wall well, fluids can be prevented from entering a stratum, effective pressure can be increased, ineffective pressure can be reduced, a wall well stabilizing function can be effectively brought into play, the drilling fluid blocking capability can be improved, the filter loss of the drilling fluid can be reduced, the quality and plugging performance of mud cakes can be improved, the inhibition of the drilling fluid can be improved, a liquid in a shaft can be prevented from entering stratum pores and cracks, the probabilityof differential pressure adhesion and tool jamming can be reduced, and in addition, the nano filming plugging agent is simple, convenient and easy in control of preparation processes, convenient andrapid to use, and high in popularization and application value.

Description

Technical field [0001] The invention relates to the technical field of petroleum exploitation, in particular to the technical field of oil well plugging agents, and more specifically to a nano film-forming plugging agent for drilling fluid used for stabilizing well walls, and a preparation method and application thereof. Background technique [0002] The stratum of petroleum reservoirs is generally located in deep strata under strong ground stress. The lithology is complex. The clay minerals are mainly illite and Imon ordered interlayers. They are not easy to disperse, and the recovery rate is greater than 80%. They are not easy to expand and the rock can be drilled. In the oil drilling operation, due to the strong ground stress, the borehole wall of the deep hard and brittle formation is prone to instability, resulting in complex well conditions such as well collapse and sticking. The main cause of wall instability is that the density of the drilling fluid is low, which is not e...

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Problems solved by technology

[0002] The strata of oil reservoirs are generally in deep strata under the action of strong in-situ stress. The lithology is complex. The clay minerals are mainly illite and illite interlayers, which are not easy to disperse. The recovery rate is greater than 80%. The hardness is higher than grade 6, and the downhole situation is complicated due to high hardness, which is prone to well collapse and pipe sticking. In addition, during oil drilling operations, due to the strong in-situ stress, the wellbore of deep hard and brittle formations is prone to instability, resulting in well The main cause of wall instability is that the drilling fluid density is low enough to balance the ground stress, resulting in mechanical instability; or the drilling fluid density is too high, exceeding the formation fracture pressure, causing the formation to break and collapse; Expansion, etc.

[0003] In the prior art, the lost circulation agent is often used to balance the effective pressure in the well for the problem of well wall instability. In addition, the addition of the plugging agent will have a greater impact on the properties of the drilling fluid, which may easily cause hidden accidents such as pipe sticking.

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